Biological Degradability Methods for Testing and Other Aspects

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Biological Degradability Methods for Testing
and Other Aspects
Market Inspection and Surveillance of Detergents
and Cleaning Products in Turkey TAIEX Seminar,
7 May 2008, Ankara Dr. Klaus TaegerProduct
SafetyRegulations, Toxicology and Ecology
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Presentation overview

• Development of EU legislation on biodegradability
  of surfactants
• Methodology principles on biodegradation
• Definition of the ten days window principle and
  applicability on assessement of surfactants
• EU legislation on biodegradability testing of
  surfactants
• Summary and conclusions

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The detergent problem in the early 1960s
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Development of the European Detergent Legislation
on Biodegradability requirements
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Biodegradation principle and analytical
measurements
Oxygen consumption
O2
Organic substance
Biomass growth
CO2
Carbon dioxide evolution
DOC removal
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Definition of primary and ultimate degradation
pathway of exemplified fatty alcohol sulfate
O-SO3Na
Fatty alcohol sulfate (parent compound)
Primary degradation
Sulfate
OH
Fatty alcohol (primary degration product)
C2
Degradation intermediates
C2
C2
Ultimate degradation
Biomass
CO2 H2O
Final products
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Surfactants Biodegradation in Screening
Tests Primary degradation vs. ultimate
degradation
Primary degradation (BiAS or MBAS)
Total degradation (DOC removal)
Ultimate degradation (O2 / CO2 minerali- sation)
degradation
Test duration days
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Methods for Testing Surfactants of the OECD 301
Series
Analytical Parameter
Method

• Screening Tests
• Oxygen consumption
• Carbon dioxide evolution
• Dissolved organic carbon removal
• Tests on primary degradation
• Specific analysis(e.g. HPLC, MBAS, BiAS)

• gt 60 pass level
• OECD 301 D, F
• OECD 301 B, 310
• gt70 acceptability is limitedOECD 301 A, E
• gt 80 pass level
• OECD 301 A, E
• OECD 303 A

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Definition of the ten days window principle in
the OECD 301 Series
Why is the 10 day time-window not applicable for
testing surfactants ?
? lt 10 days ?
O2 / CO2
Time duration days
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Essential conditions for the ready biodegradabilit
y assessment

• Inoculum / bacteria not adapted
• Low biomass / bacteria density relation
• Kinetic term fulfilling the 10 days window
• Defined pure substance

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Biodegradation of a typical nonionic surfactant
(1)
Molecular mass distribution at day 0
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Biodegradation of a typical nonionic surfactant
(2)
Molecular mass distribution at day 6
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Non-applicability of the ten days principle for
surfactants scientific arguments

• Biodegradation of surfactants are generally
  characterised by a multiphase kinetics due to a
  multi-component substrate
• Potential intermediate metabolites may have
  metabolic rates which are different from the
  parent compound
• Some metabolites interfere with the degradation
  process by inhibiting the transformation of the
  parent molecule

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Modified Carbon dioxide evolution test with
additional carbon determination - CO2 /
DOC-Combination-Test -
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Biodegradation and Elimination curve of a
secondary alcohol ethoxylate in the CO2 /
DOC-Combination Test
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Biodegradation and Elimination curve of a
branched fatty acid in the CO2 / DOC-Combination
Test
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Limitation of methodical biodegradation testing

• Bacterial toxicity
• Volatility
• Water solubility
• Mixtures
• Adsorption / films

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EU Legislation as a step-by-step testing scheme
(derogation for Industrial Institutional
applications)
Screening tests on readily biodegradability
OECD 301 B, C, D, F OECD 310
above 60 limit
allowed for market
below 60 limit
Primary biodegradability screening
and/or confirmatory
below 80 limit
not allowed for market
pass 80 limit
Simplified complementary Risk Assessment
acceptable risk
allowed for market
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EU Legislation complementary Risk Assessment
(Annex IV)

• Identify of the surfactant
• Exposition Function and expected volume
• Information about potential metabolites
• Further biodegradation studies
• preadapted inoculum
• verification of inherent biodegradability OECD
  302 A or B including OECD 303 A
• Toxicity testing of metabolites
• Information about the potential of
  bioaccumulation of metabolites

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Aceptance of surfactants biodegradation under EU
legislation

• Screening tests on readily biodegradability
  according to the OECD 301 Series and OECD 310
  without application of the 10 days window
  principle
• Acceptability of data based on DOC removal which
  show a definite sigmoid biodegradation curve
• Read across by interpolation between a similar
  surfactant group
• Step-by-step testing scheme by derogation for
  Industrial Institutional applications

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Summary and Conclusions

• In the 1960 the assessment of the
  biodegradability of surfactants based on the loss
  of surface tension (primary biodegradation)
• Over decades the EU legislation implemented the
  ultimate biodegradation (mineralisation)
• The ten days window principle of the readily
  biodegradability screening tests does not apply
  for surfactants, because surfactants are
  multi-component mixtures
• In cases of failing pass levels a derogation for
  Industrial Institutional applications allowes a
  step-by-step testing scheme of surfactants